-There are 2 protagonists instead of just one (the first one being the Chief). Maybe we can be able to play as the Arbiter as he escapes/confronts his assailants and the rebellion. So there is a slight possibility that we might be fighting Covenant Loyalists, not as the Chief but as the Arbiter.

-We might be able to fight with/against SPARTAN IVs, ONI, and UNSC operatives in the Legendary Planet. So far I think the "Legendary" planet is actually Onyx and if this is true, then there is the slightest possibility that we may or may not encounter Dr. Halsey, Mendez, and the remaining SPARTAN IIs and IIIs.

-Buck may make a comeback.

-If Precursors do make an appearance in this game then there is a possibility that Forerunners will too.

-Chief will save the universe.

-Halo 4 will have a cliff-hanger ending just like Halo 2.

-Multiplayer might just have it's own storyline regarding the RvB thing Frank mentioned in the Video they released.

I'm your Commander! - kill 100 grunts with an energy sword (10G)Set Start - kill all enemies in the enemy team in a Team Slayer match (25G)I could if I would - Save all marines in the level Halo (10G)This is HALO! - push a zealot off a cliff (10G)The opposite side - return the enemy flag (5G)The first of many - Finish the campaign in Legendary (75G)Halo 2? I see U! - Play one of z_team's halo 2 maps (5G)Gameplay... enhanced! - Play all the CMT SPv1 maps (25G)I stuck you - Stick 100 enemies in campaign (25G)Million worm body - Kill 50 hunter in campaign (10G)Sup... - Earn a flood buddy (5G)